Conclusion

The probably most interesting conclusion of this survey is the rarely so obvious observation how closely related an initially purely basic research can be to applied materials research. What started out as a study of the elemental properties of cosmic dust evolved into an investigation of the degradation of space exposed surfaces and the safe differentiation between cosmic and terrestrial particles on materials surfaces. Thus the considerable danger of a certain rocket fuel technology for the life time of satellites in LEO could clearly be demonstrated.

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Fig. 8. shows a photo and a secondary electron image (of a scanning electron microscope) of a particle impact on a solar cell sample of the Hubble Space Telescope (Heiss & Stadermann, 1997)

This consequently caused the elimination of this technology in spite of previous great political tensions caused by this discussion. A further respective consequence was the introduction of small protective shields in flight direction especially for satellites in LEO which should operate for a long time. Basic research has thus definitely influenced applied space technology. The positioning of satellites in LEO for long duration is of great importance not only for military reconnaissance but also for modern communication and positioning systems, for global catastrophe survey and many other geopolitical surveys. Without the availability of proper topochemical and analytical technology a respective life time evaluation would not have been feasible. It seems also worth mentioning that SIMS is the key topochemical method for these investigations. The need to analyze particles in the single micrometer range triggered the development of a new SIMS-instrument generation with a much advanced lateral resolution in the upper nanometer range – the NanoSIMS 50 of CAMECA (Schuhmacher et al., 1999). Respective mass spectrometric results are not presented here in order not to unduly lengthen this article. The most important results are given in (Stadermann, 1990 and 1992).

The Hubble Space Telescope is powered by solar cells which are mounted on two flexible solar array wings. These solar array wings have been replaced after almost four years in space. One of these solar array wings was brought back to earth, while the other one was jettisoned. The retrieving of this solar array was a unique possibility for the investigation of the conditions in the low earth orbit. This wing was exposed to a permanent flux of micro particles. Since it was of interest whether these particles were man-made debris or micro – meteoroides, the European Research and Technology Centre (ESTEC) decided to disassemble two of the ten solar panel assemblies for further investigation in which our group participated.

It is not surprising that the investigation of Interplanetary Dust has developed to a most important scientific discipline in the Space Sciences. Dust is an essential component throughout space. It constitutes a considerable part of the total matter of our universe (Brownlee, 1978, Grun et al., 2001). Consequently, material degradation by micrometeorites is one of the common phenomena space flights have to cope with. It is also a fascinating result of this young scientific discipline that a part of the particles which come into the vicinity of our earth will eventually be trapped by the earth’s gravity pull. Hence, our planet is collecting cosmic dust daily in a quantity of several tons. This leads to the conclusion that cosmic dust is not as exotic a material as we usually think. And every time we dust our window sills or book shelves we can be sure to clean particles from Deep Space, too.

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